Is the intensity of tornadoes increasing in the United States, (or, for that matter, falling)? It’s a perennial question.

NOAA gives us some clues, with their charts of EF-1+ and EF-3 to EF-5 tornadoes since 1954. (NOAA ignore EF-0’s, because many more of these weak tornadoes get to be reported nowadays than in the past because of Doppler radar, better reporting practices, increasing population etc – for the background on this, see here.)

[ The original Fujita grading system, using “F” numbers, was replaced in 2007 by the Enhanced Fujita scale, hence “EF” numbers. The new system was designed to ensure compatibility with the original Fujita scale- see here. All references to either Fujita or Enhanced Fujita should be regarded as interchangeable]

But these graphs tell us little about the distribution within the totals. For instance, could there be more EF-4’s relative to EF-3’s?